Stabilizing fatty composition



Patented June 24, 1941 STABILIZIN G FATTY COMPOSITION George D. Martin, Nitro, W. 'Va., assignor to Monsanto Chemical Company, St. Louis, Mo., a

corporation of Delaware No Drawing. Application April 22, 1939, Serial No. 269,413

7 Claims.

This invention relates to the stabilization of compositions containing a fatty component and particularly to the prevention of their decomposition or rancidification.

It is well known that soap and especially white soap tends to deteriorate upon aging as evidenced by development of color and rancid odor. This deterioration is due to the oxidation of the fatty acid molecule whereby simpler products such as aldehydes and-ketones are formed. It is known that various agents such as heat, sunlight, ultraviolet light and certain metals such as copper greatly accelerate these changes. It is obviously desirable to counteract these accelerating agents and the natural tendency of soaps to deterioratewith age.

A number of organic reagents have been found to exert 'a preservative action upon soap and among such compounds are a number of aro-.- matic amines. Certain secondary aromatic amines, for example, are known to prevent rancidity in an ordinary soap composition for considerable periods of time. However, the aromatic amines possess the serious disadvantage ofinducing the formation of color in the soap. Thus, in contrast to preventing a color formation due to deterioration of the soap they actually exert a discoloring influence of their own. Furthermore, certain compounds of the prior art impart a distinctive odor to the soap. Prior attempts have been made to modify the properties of amines known to exert a stabilizing influence on soap and to find related materials which retained the properties desired but were without the objections noted above. For example, aldehyde reaction products of amines have been employed. ,In general the result has been to either destroy or materially decrease the rancidity inhibiting properties or to fail to avoid the usual objections to the parent compounds.

This invention has as an object the preservawhat of a related compound, is one of the arcmatic amines described in the prior art and is a good soap antioxidant. as regards preventing rancidity but causes a marked discoloration which, in the case of white soaps, ranges from yellow to brown. The action of amines containing heavier hydrocarbon substituents was in-' -pounds investigated were beta naphthyl o-bition of soaps and the like and more particularly to retard'the development of color and rancidity in soap. A further object is to provide a soap stabilizer which is stable to light. A still further object is the preparation of a new and improved soap.

These and further objects are accomplished by the invention herein disclosed by the use of di-pbiphenyl amine. This compound has been discovered to be highly effective in preventing rancidity without forming objectional color or odor.v

The discovery of the valuable properties of dip-blphenyl amine represents an important advance in the art. Diphenylamine, which is somephenyl amine, alpha naphthyl p-biphenyl amine, alpha naphthyl o-biphenyl amine and beta naphthyl o-(p, p' dichlor) biphenyl amine. It was found that in every case the development of rancidity was prevented for at least as long a period as in the case of diphenyl amine and, in general, for longer periods but when soaps containing small proportions of these materials were exposed to direct sunlight they discolored in even a shorter time than soap treated with diphenyl amine. However, an exception was found in the case of di-p-biphenyl amine which was not only highly effective in preventing rancidity but was non-discoloring and in general exhibited good light stability in the soap composition.

The following are typical methods employed in testing the materials and are specific embodiments .of the invention showing the useful and valuable properties of di-p-biphenyl amine and are intended to illustrate the invention but in nowise to limit the same.

A substantially neutral soap was prepared by saponifying a mixture of substantially three parts by weight of an edible taliow and substan-- tially one part by weight of cocoanut oil with sodium hydroxide. Substantially 0.1% based on the weight of the soap of di-p-biphenyl amine was incorporated therein by a suitable means. Five grams of the treated soap were placed in a 250 c. c. iodine flask and a piece of filter paper saturated with water was torn to small pieces and placed in the flask. The flask was then tightly stoppered and placed in an oven maintained at a constant temperature of 50 C. At

' the end of each day the color of the soap under treated with diphenyl amine and-tested in the same manner was found to be 40 days.

As a further specific embodiment of the invention samples of the soap treated with di-pbiphenyl amine as described above were exposed to direct sunlight and compared to the untreated soap and soap treated with diphenyl amine. At the end of 100 hours exposure the soap treated with diphenyl amine had discolored a dark tan whereas the soap treated with dl-p-biphenyl amine showed onlya slight discoloration evidenced by a light cream color and was in every case equal to or superior to the blank.

It was further noted that di-p-biphenyl amine did not impart an odor to the soap.

From the data hereinbefore set forth it is readily shown that di-p-biphenyl amine is an important soap stabilizer.

The amount of the preferred material which may be added to the ordinary soap or soap stock, for effecting the desired result may be varied, but in general it will be found that good results may be obtained by adding, upon a weight basis, from 0.01% to 1.0% of the stabilizing agent to the soap or soap stock.

In operating the present invention the stabilizing agent may be introduced at any stage of the process of soap manufacture. For example, after the fatty acid has been obtained in the usual manner and has been saponified to produce a soap stock, the products comprising the preferred stabilizers may be incorporated therein. The soap product may then be dried in the usual manner and may be marketed in cakes, flakes or any other form as may be desired. Further, if desirable the stabilizing agent may be incorporated into the dry soap in the well known crutching process. Moreover, the stafollowing claims attached hereto as part of the I specification.

What is claimed is:

1. An oxldizable fatty material having incorporated therein a di-biphenyl amine in an amount suflicient to retard the development of color and rancidity to a substantial degree.

2. A soap having incorporated therein a di-pbiphenyl amine in an amount suflicient to retard the development of color and rancidity to a substantial degree.

3. A soap having incorporated therein di-pbiphenyl amine in an amount 'sufilcient to retard the development of color and rancidity to a substantial degree.

4. The method of fatty material which therein a di-biphenyl amine in an amount sufficient to retard the development of color and rancidity to a substantial degree.

5. The method of preserving soap which comprises incorporating therein a di-p-biphenyl amine in anamount sumcient to retard the development of color and racidity to a substantial preserving an oxidizable degree.

6. The method of preserving soap which comprises incorporating therein di-p-biphenyl amine in an amount suflicient to retard the development of color and rancidity to a substantial degree.

"7. An alkali metal water soluble soap rendered resistant to discoloration and the development bilizing agent may conveniently be added to the 40 oils, fats or fatty acids before saponification.

Other methods of testing the stability of fatty of rancidity by having incorporated therein from 0.01% to 1.0% of di-p-biphenyl amine.

GEORGE D. MARTIN.

comprises incorporating- 

